Start at framebuffer drawing

src/kernel/boot/kmain.c

@@ -20,18 +20,16 @@ registers *divbyzero(registers *r) {
 
 void kmain(uint64_t multiboot_magic, void *multiboot_data)
 {
+    multiboot_init(multiboot_magic, P2V(multiboot_data));
+
+    cpu_init();
+    memory_init();
+
     vga_init();
     
     debug("Started kernel\n");
-
-    cpu_init();
-
-    multiboot_init(multiboot_magic, P2V(multiboot_data));
-
     debug_info("Kernel loaded with command line: \"%s\" by <%s>\n", kernel_boot_data.commandline, kernel_boot_data.bootloader);
 
-    memory_init();
-
     bind_interrupt(0, divbyzero);
 
     // Force a divide by zero error

src/kernel/boot/multiboot.c

@@ -29,17 +29,6 @@ struct mmap {
     struct mmap_entry entries[];
 }__attribute__((packed));
 
-struct fbinfo {
-    uint64_t framebuffer_addr;
-    uint32_t framebuffer_pitch;
-    uint32_t framebuffer_width;
-    uint32_t framebuffer_height;
-    uint8_t framebuffer_bpp;
-    uint8_t framebuffer_type;
-    uint8_t reserved;
-    uint8_t data[];
-}__attribute__((packed));
-
 static int parse_multiboot2(struct taglist *tags)
 {
     struct mmap *mmap;
@@ -60,7 +49,8 @@ static int parse_multiboot2(struct taglist *tags)
                 kernel_boot_data.mmap_len = (tag->size - 8)/mmap->entry_size;
                 kernel_boot_data.mmap_size = (tag->size - 8);
                 break;
-            case 8:
+            case MBOOT2_TAG_FBINFO:
+                kernel_boot_data.fbinfo = (void *)tag->data;
                 break;
         }
         
@@ -101,10 +91,18 @@ int multiboot_get_memory_area(size_t index, uintptr_t *start, uintptr_t *end, ui
 int multiboot_page_used(uintptr_t page)
 {
     #define within_page(st, l) (((uintptr_t)st + l) > page && (uintptr_t)st < (page + PAGE_SIZE))
+    
+    size_t fb_size = 0;
+    uintptr_t fb_start = 0;
+    if(kernel_boot_data.fbinfo) {
+        fb_start = kernel_boot_data.fbinfo->framebuffer_addr;
+        fb_size = kernel_boot_data.fbinfo->framebuffer_pitch*(kernel_boot_data.fbinfo->framebuffer_height + 1);
+    }
     if(
         within_page(kernel_boot_data.bootloader, strlen(kernel_boot_data.bootloader)) ||
         within_page(kernel_boot_data.commandline, strlen(kernel_boot_data.commandline)) ||
         within_page(kernel_boot_data.mmap, kernel_boot_data.mmap_size) ||
+        within_page(fb_start, fb_size) ||
     0) {
         debug("Page %x used\n", page);
         return 1;

src/kernel/boot/multiboot_header.S

@@ -10,6 +10,15 @@ Multiboot2Header:
 
 //; Multiboot tag list
 
+.short 5 //; Request graphics mode
+.short 0
+.long 20
+.long 0
+.long 0
+.long 0
+
+.long 0 //; Pad to multiple of 8 bytes
+
 .short 0 //; End tag
 .short 0
 .long 8

src/kernel/drivers/framebuffer.c

@@ -0,0 +1,31 @@
+#include <stdint.h>
+#include <memory.h>
+#include <multiboot.h>
+
+void framebuffer_init(struct fbinfo *fbinfo)
+{
+    size_t fb_size = fbinfo->framebuffer_pitch * (fbinfo->framebuffer_height+1);
+    uintptr_t fb_end = fbinfo->framebuffer_addr + fb_size;
+
+    for(uintptr_t p = fbinfo->framebuffer_addr; p < fb_end; p += PAGE_SIZE)
+    {
+        vmm_set_page(kernel_P4, (uint64_t)P2V(p), p, PAGE_WRITE | PAGE_PRESENT);
+    }
+
+    uint8_t *fb = P2V(fbinfo->framebuffer_addr);
+
+    for(uint32_t y = 0; y < 1; y++)
+    {
+        for(uint32_t x = 0; x < fbinfo->framebuffer_width; x++)
+        {
+            unsigned int bpp = fbinfo->framebuffer_bpp/8;
+            unsigned int loc = \
+                y*fbinfo->framebuffer_pitch + \
+                x*(bpp);
+            fb[loc++] = 0xFF;
+            fb[loc++] = 0;
+            fb[loc] = 0xFF;
+        }
+    }
+
+}

src/kernel/drivers/vga.c

@@ -1,6 +1,9 @@
 #include <vga.h>
 #include <memory.h>
 #include <ports.h>
+#include <multiboot.h>
+#include <stddef.h>
+#include <debug.h>
 
 #define VGA_COLS 80
 #define VGA_ROWS 24
@@ -26,15 +29,29 @@ struct vga_cell buffer[VGA_SIZE];
 uint64_t cursor;
 uint8_t format;
 
+static int vga_setup = 0;
+static int vga_type;
+
 void vga_init()
 {
-    vidmem = VGA_MEMORY;
+    struct fbinfo *fbinfo = kernel_boot_data.fbinfo;
-    memset(vidmem, 0, VGA_SIZE*sizeof(struct vga_cell));
+    vga_type = fbinfo->framebuffer_type;
+    switch(vga_type)
+    {
+        case 1:
+            framebuffer_init(fbinfo);
+            break;
+        case 2:
+            vidmem = VGA_MEMORY;
+            memset(vidmem, 0, VGA_SIZE*sizeof(struct vga_cell));
+            format = 0x07;
+            break;
+    }
 
-    format = 0x07;
+    vga_setup = 1;
 }
 
-void movecursor()
+static void movecursor()
 {
     outb(VGA_ADDRESS_PORT, VGA_REGISTER_CURSOR_POS_LOW);
     outb(VGA_DATA_PORT, (uint8_t)(cursor & 0xFF));
@@ -42,12 +59,13 @@ void movecursor()
     outb(VGA_DATA_PORT, (uint8_t)((cursor >> 8) & 0xFF));
 }
 
-void flush()
+static void flush()
 {
-    memcpy(vidmem, buffer, sizeof(buffer));
+    if(vga_setup)
+        memcpy(vidmem, buffer, sizeof(buffer));
 }
 
-void scroll()
+static void scroll()
 {
     while(cursor >= VGA_SIZE)
     {
@@ -59,15 +77,20 @@ void scroll()
 
 void vga_write(char c)
 {
-    switch(c)
+    switch(vga_type)
     {
-        case '\n':
+        case 2:
-            cursor += VGA_COLS - VGA_COL(cursor);
+            switch(c)
+            {
+                case '\n':
+                    cursor += VGA_COLS - VGA_COL(cursor);
+                    break;
+                default:
+                    buffer[cursor++] = (struct vga_cell){.c = c, .f = format};
+            }
+            scroll();
+            flush();
+            movecursor();
             break;
-        default:
-            buffer[cursor++] = (struct vga_cell){.c = c, .f = format};
     }
-    scroll();
-    flush();
-    movecursor();
 }

src/kernel/include/multiboot.h

@@ -13,6 +13,18 @@
 
 #ifndef __ASSEMBLER__
 #include <stddef.h>
+
+struct fbinfo {
+    uint64_t framebuffer_addr;
+    uint32_t framebuffer_pitch;
+    uint32_t framebuffer_width;
+    uint32_t framebuffer_height;
+    uint8_t framebuffer_bpp;
+    uint8_t framebuffer_type;
+    uint8_t reserved;
+    uint8_t color_info[];
+}__attribute__((packed));
+
 struct kernel_boot_data_st{
     int multiboot_version;
     char *bootloader;
@@ -20,6 +32,7 @@ struct kernel_boot_data_st{
     size_t mmap_size;
     unsigned int mmap_len;
     void *mmap;
+    struct fbinfo *fbinfo;
 };
 
 #define MMAP_FREE 1

src/kernel/include/vga.h

@@ -1,8 +1,12 @@
 #pragma once
 #include <memory.h>
+#include <multiboot.h>
 
 #define VGA_MEMORY P2V(0xB8000)
 
 // drivers/vga.c
 void vga_init();
 void vga_write(char c);
+
+// drivers/framebuffer.c
+void framebuffer_init(struct fbinfo *fbinfo);